Super absorbent polymers (SAPs) can absorb water up to a few hundred or even a few thousand times their own mass. Their special physical structure, unique chemical composition, and characteristics of high water absorption capacity allow super absorbent polymers to be widely used in agriculture, horticulture, forestry and other industries to relieve drought and reserve water for farmland, seedling protection, and crop yield improvement. However, the amount of super absorbent polymers applied is an important parameter to evaluate. Applying the incorrect amount can result in either no effect, or soil permeability may be compromised if excess amounts are used. This can cause plant roots to have difficulty breathing or to have root rot. To explore the influence of super absorbent polymers on the growth and nutritional characteristics of Festuca arundinacea L. on gangue waste, three matrix gradients were set up with different weight ratios of gangue/soil. The matrix of each gradient was added into the super absorbent polymer in three different qualities. Ten treatments in total, including CK, were set up in this paper. The height growth, biomass, nutritional characteristics and SPAD (Soil and Plant Analyzer Development) value of Festuca arundinacea L. under different treatments were observed. The effects of different treatments on the gangue matrix and on Festuca arundinacea L. growth were analyzed to determine the reasonable dosage of super absorbent polymer to be added to the gangue wasteland for vegetation recovery. This provides a theoretical basis and technical support for this practical application. The results show that adding super absorbent polymers helps strengthen the gangue matrix's ability to hold water, increasing the water available to the plants, which promotes plant growth and biomass increase. The super absorbent polymer mainly impacts aboveground biomass, while the underground biomass is mainly affected by the weight ratio of the gangue/soil; for treatments where the weight ratio of gangue/soil is the same, adding 1 g/kg super absorbent polymer accelerates Festuca arundinacea L. growth; adding 2 g/kg super absorbent polymer to the matrix helps Festuca arundinacea L. quickly adapt to the matrix environment and the daily average growth rate reaches peak value 2 weeks after the seedling emergence. Adding super absorbent polymer to a gangue matrix enhances the gangue's ability to hold fertilizer and to supply nutrients to plants. Festuca arundinacea L. can promote growth by transferring nutrients in the gangue matrix from underground plant parts to aerial parts. Phosphorus absorption was most efficient when 1 g/kg super absorbent polymer was added. Super absorbent polymers affect photosynthesis parameters of blade leaves by imposing impact on plant water use efficiency. Therefore, adding super absorbent polymers can increase the SPAD value of the blade leaf. From comprehensive comparisons of plant height, biomass, nutrition characteristics and leaf SPAD values of Festuca arundinacea L. under different treatments, treatment No. 6 (weight ratio of gangue/soil is 750:250, with 2 g super absorbent polymer) and treatment No. 8 (weight ratio of gangue/soil is 500:500, with 1 g super absorbent polymer) were the optimal conditions found to help Festuca arundinacea L. grow on gangue waste.